1. Field of the Invention
This invention relates generally to photo-couplers wherein input electrical signals are optically coupled to an output, and more particularly to the photo-coupler with delay function wherein generation of output signals is delayed relative to the input signals.
2. Description of the Prior Art
The photo-coupler is a composite device wherein the input signals are coupled to the output with input and output terminals, that is, front and rear portions of a circuit electrically insulated. The photo-coupler has an advantage in protection of the circuit from electrical noises, so that the photo-coupler has been used in wide fields of application.
Where the photo-coupler is provided with a delay function, the output signals are, conventionally, delayed by means of an integrator circuit or the like.
Such an expensive delay circuit as the integrator circuit is thus required when the delay function is applied between the input and output signals in the case of the photo-coupler. Accordingly, provision of the expensive delay circuit complicates the circuit arrangement and increases the production cost of the photo-coupler.